In the 8.x-3.x branch of search_api_solr the config files for Solr are generated by Drupal. The default synonyms file it generates just has drupal, durpal. Would be good if it could pull the synonyms from this module. Likely need to implement hook_search_api_solr_config_files_alter().
Active
2.0
Code
Not all content is available!
It's likely this issue predates Contrib.social: some issue and comment data are missing.
This would indeed be nice, probably in a PostConfigFilesGenerationEvent event subscriber.
Made an initial start on this, we will need to compile the synonyms to add to the files post config creation.